1. Field of the Invention
The invention is drawn to novel biocontrol agents for control of Fusarium head blight.
2. Description of the Prior Art
Fusarium head blight (FHB) is a devastating disease of wheat and barley throughout the semi-humid and humid cereal producing regions of the world (McMullen et al., 1997; Muthomi et al., 2002; Yu. Gagkaeva and Yli-Mattila, 2004). FHB is caused primarily by Fusarium graminearum Schwabe Group 2 (Aoki and O'Donnell, 1999) (perfect state=Gibberella zeae (Schwein.) Petch). In addition to causing grain yield loss, G. zeae can produce mycotoxins such as the estrogenic toxin zearalenone (F-2) (Hesseltine et al., 1978) and the trichothecene deoxynivalenol (DON, vomitoxin) (Snijders, 1990) that can have a deleterious effect on grain quality (Cardwell et al., 2001) and animal health (Marasas, 1991; Beardall and Miller, 1994; Pestka and Bondy, 1994).
Reducing the impact of FHB on grain production and quality remains an intractable problem. Fungicides sometimes have reduced FHB (Wilcoxson, 1996; Suty and Mauler-Machnik, 1997; Jones, 1999), but residues, reports of fungicide resistance and instances of DON content increases in grain can be concerns with their use (Mauler-Machnik and Zahn, 1994; Ramirez et al., 2004; Chen et al., 2000; Gale et al., 2002). Although the development of resistant cultivars or anatomically altered varieties (Legzdina and Buerstmayr, 2004) of small grains holds promise in reducing FHB, highly resistant cultivars with ideal agronomic traits have not been developed (Johnston, 1994; Bushnell et al., 1998; Bai et al., 2000). The genetic diversity of G. zeae (O'Donnell et al., 2004, McCallum et al., 2004; Walker et al., 2001; Cumagun et al., 2004) raises concerns regarding how durable the efficacy of fungicides and resistant cultivars will be. Conventional tillage of fields is partially effective in reducing pathogen inoculum production and, concomitantly, FHB (Miller et al., 1998; Dill-Macky and Jones, 2000; Pereyra et al., 2004), but minimum tillage is the preferred agricultural practice for soil conservation. Considering the potential of long distance inoculum dispersal and the diverse crops that can act as alternative hosts of the pathogen (Chongo et al., 2001), crop rotation is an untenable solution.
Biological control of FHB has attracted considerable interest since the mid 1990's, and significant advances have been achieved (Perondi et al., 1996; Bujold et al., 2001, Schisler et al., 2002b; da Luz et al., 2003; Gilbert & Fernando, 2004). Public acceptance, compatibility with other disease management measures, and durability are all favorable factors in support of developing strategies for biologically controlling FHB.
However, despite these and other advances, the need remains for improved microorganisms for use in the biological control of FHB.